Outline

Objective

Functional information concerning the surrounding brain are mandatory for a good clinical outcome in brain tumour surgery. The value of fMRI to detect the motorcortex and the Broca area is widely accepted today. If an appropriate paradigm is used, short-term memory areas can be visualized as well. Obviously this information must be integrated into cranial neuronavigation for an appropriate intraoperative use. We report our first experiences with the direct integration of short-term memory fMRI into cranial neuronavigation.

Methods

From January 2001 to March 2002, 14 patients were operated on for intracranial tumours with short-term memory fMRI imaging. A thin-sliced gadolinium enhanced T1 weighted MRI was always used for anatomical orientation. fMRI using the "two-back-paradigm" was done during the same session and superimposed. Preoperatively the short-term memory of all patients was additionally tested by 16 different standard memory items (like mini mental state, alertness test, trailmaking etc.). Three to 12 months postoperatively fMRI was done in 12 patients, and in all 14 patients the mentioned test items were repeated.

Results

Three from 14 patients subjectively complaint of an impaired short-term memory, 11/14 noticed no difference. Postoperative fMRI, which was undertaken in 12 patients so far, demonstrated an unchanged BOLD effect in 11/12 patients, and was missing in 1 patient. This patient deteriorated slightly in the above-mentioned tests, 13/14 remained almost unchanged.

Conclusions

In contrast to the motorcortex or Broca area, no electrophysiological method is available to detect short-term memory areas intraoperatively. fMRI, integrated into neuronavigation, is able to visualize these brain areas and help to preserve them during removal of intrinsic brain tumours.